The present invention relates to a shuttering or sheathing element of hard expanded plastics material for the concrete casing method of construction, comprising two panels arranged parallel to each other and having a tongue and groove structure at their edges, and webs interconnecting the panels.
A shuttering element corresponding to the kind referred to above is disclosed in the German Patent Specification No. 1,784,573. The two panels forming the corresponding subsequent insulating jackets are identical in thickness in the case of this element. This results in the disadvantage that, since the thickness of the panels is comparatively great to secure a very satisfactory heat barrier, the period of vapour traversal through the cavity-side panel forming the inner jacket is of considerable length. The humidity exchange between the wall of the structure and the internal space is thereby completed in comparatively sluggish manner, which has an unfavourable effect on the interior environment. It has been observed moreover that the possibility of anchoring fastening means, e.g. dowels, needs improving so that even heavy objects may be fastened to the walls by means of simple dowels.
It is an object of the invention to provide an improved shuttering element of the kind referred to above, so that, whilst assuring an excellent heat barrier, a comparatively rapid vapour permeability at the interior side, a more satisfactory exploitation of the poured concrete as a heat store, as well as secure anchoring of fastening means, are accomplished.